X-ray generating apparatus

a generation apparatus and x-ray technology, applied in the micro field, can solve the problems of inability to increase the x-ray dosage, the x-ray focus or failure, and the x-ray emission cannot be stopped, so as to promote the lowering of the temperature on the target surface, the effect of easy dissipation of heat generated in the targ

Inactive Publication Date: 2007-05-08
SHIMADZU CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0010]This invention has been made having regard to the state of the art noted above, and its primary object is to provide an X-ray generating apparatus with improved local heat-dissipation performance of a target, for extending the life of the target, increasing the operating ratio of the apparatus, and improving X-ray intensity.

Problems solved by technology

However the portion of the target where an electron beam collides becomes high temperature and the target material evaporate and wear away, the X-ray tube will cease emitting X-rays in due time.
The evaporation will result in the inconvenience of enlarging the X-ray focus or failing X-rays, which requires a maintenance operation such as a change of the X-ray tube or the target.
When a powerful electron beam is emitted in order to increase X-ray dosage, the target material will evaporate momentarily to render the increase in X-ray dosage impossible.

Method used

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Examples

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example 1

[0116]The example shown in FIG. 8 corresponds to claim 8, and the shape of bore 21 differs from the foregoing embodiment. Specifically, the bore 21 has a tapered shape with the inner wall surface converging from the electron beam incoming side toward the target layer 18. That is, the inner wall surface of the bore 21 is tapered to correspond to the shape of electron beam B with the forward end converged in the direction of movement by a lens. The taper has an angle θ which, preferably, is several to 60 degrees, for example, although this depends on the level of convergence of the electron beam B.

[0117]This construction can guide the tapered electron beam B to the target layer 18 without obstructing movement of the electron beam B. In addition, the portion of the surface solid 20 in tight contact with the target layer 18 can be located near where the electron beam B collides with the target surface. Consequently, the temperature of the heated portion on the target surface is lowered ...

example 2

[0119]The example shown in FIG. 9 corresponds to claim 9, in which surface solids 20a–20c are formed in multiple layers on the target surface. The multilayer structure is formed by repeating a film forming process to change materials. For example, the lowermost layer 20a contacts tight with the target layer 18 and is formed from a highly heat-conductive material such as copper or silver. The next, intermediate layer 20b is formed from gold that is highly heat conductive and evaporates in a relatively small amount. The finally, uppermost layer 20c is formed from tungsten or molybdenum which is a high melting point and evaporates in a very small amount.

[0120]With this construction, the intermediate layer 20b and uppermost layer 20c prevent evaporation of the lowermost layer 20a while maintaining the heat-dissipation effect of the lowermost layer 20a. This construction reduces evaporating and so thinning of the surface solid 20 by target heat caused by electron beam irradiation, and ma...

example 3

[0122]The example shown in FIG. 10 corresponds to claim 10, in which surface solids 20a–20c are formed in multiple layers on the target surface. The multilayer structure is arranged adjacent radially of the electron beam. It is preferred in this case that the layer 20a near the electron beam is formed from a high melting point material, and the outer layers 20b,20c are formed from a highly heat-conductive material.

[0123]With this construction, the layer 20a is the highest temperature among layers but evaporation is suppressed by its material nature and by the heat-dissipation of the layer 20b,c. Thus, the X-ray generating apparatus can be used over a long period of time.

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Abstract

This invention relates to a microfocus X-ray tube having a heat-dissipation solid formed on the target adhesively. Specifically, the heat-dissipation solid defining an opening is formed on the target surface irradiated with an electron beam. Heat generated adjacent the target surface by impingement of an electron beam having passed through the opening is promptly distributed by heat conduction through the surface solid. The heat-dissipation solid contributes to lowering of a surface temperature of the target layer with which the electron beam collides, and a reduction of evaporation of a material forming the target, thereby extending an X-ray generating time.

Description

BACKGROUND OF THE INVENTION[0001](1) Field of the Invention[0002]This invention relates to an X-ray generating apparatus for a non-destructive X-ray inspecting system or X-ray analyzing system. Particularly, the invention relates to an apparatus having a very small X-ray source sized in the order of microns to obtain fluoroscopic images of a minute object. More particularly, the invention relates to a microfocus X-ray tube.[0003](2) Description of the Related Art[0004]Conventionally, X-ray generating apparatus of the type noted above are operable according to the following principle. First, electrons (Sa [A]) are emitted from an electron source maintained at a high negative potential (−Sv [V]) in a vacuum, and are accelerated by a potential difference between the electron source and ground potential 0V. Next, the accelerated electrons are converged to a diameter of 20 to 0.1 μm with an electron lens. The converged electron beam collides with a solid target formed of metal (e.g. tung...

Claims

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Application Information

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Patent Type & Authority Patents(United States)
IPC IPC(8): H01J35/08G21K5/08H01J35/12H01J35/14H01J35/30
CPCH01J35/12H01J2235/1204H01J2235/1291H01J2235/186H01J35/186
Inventor UKITA, MASAAKI
Owner SHIMADZU CORP
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